Polling slows down bandwidth

[Ed Maste]

On Sat, Oct 30, 2010 at 12:32:19PM +0100, Paul Thornton wrote:

> I've been doing testing with FreeBSD 8 and em interfaces recently, and
> my experience agrees with Chuck's statement - that polling makes things
> worse when you use new (anything in the last 2 or 3 years) hardware with
> good quality gigabit ethernet interfaces.

There are some deficiencies in the current polling algorithm that will
cause it to perform less than optimally (it will temporarily stop
processing packets even though it is consuming less CPU than requested).
I have some changes that I plan to bring into the tree to improve this
situation.  For recent high quality hardware though I expect you'll get
roughly equivalent performance from polling and standard opteration.

-Ed